Pigment and compositions thereof



obtain the desired color.

United States atent-"C PIGMENT AND COMPOSITIONS THEREOF Robert E. Fearon, Tulsa, Okla assignor to Electro Chemical Laboratories Corporation, Tulsa, Okla, a corporation of Delaware No Drawing. Application April 29,1953 Serial No. 352,039

14 Claims. (Cl. 250-449) This invention relates to new compositions of matter and to the use of such compositions in the preparation of inks possessing novel and very desirable properties. More particularly, the present invention concerns a novel type of ink in which the principal pigment compound thereof is an azo derivative having the probable structural formula:

Patented May 27, 1958 sired of a drawing ink because it is impractical to maintain the desired carbon content in the ink. Even with the use 'of this ink, however, clogging will eventually occur, and a diflicult cleaning operation becomes necessary.

The present invention contemplates an ink utilizing a black pigment which 'is homogeneous and extremely soluble in water. The homogeneous black pigment generally resembles the ferroso-ferric tannate blacks of blue-black ink, except in water solubility. The contemplated class of pigments are opaque and print excellently, as is required of drawing ink. The black pigments also are readiiy susceptible of alteration through the use of ink eradicators, permitting new lines to be drawn over the eradicated area-after a brief period of drying-without blotting of the newly-applied ink. This ready removability of the ink pigment avoids the costly and paperdestroying erasures resulting from the correction of mistakes when using carbon-type inks.

An important object of the present invention is to provide a method of manufacture for a homogeneous black, brown or sepia ink especially adaptedfor contactprinting.

Another object of this invention is to provide a method of manufacture for various other colors of ink which are chromatographically homogeneous and especially adapted for contact printing.

A further object of this invention is to provide a method of manufacture of a pure water-soluble dyestufi containing an organic portion and a metal ion such as iron or cobalt. I also contemplate a method of manufacture of an azo coupled polyhydric phenol capable of reacting with these metal ions to form coordination complexes. It is another object to provide such a method wherein the azo coupled groups attachedto the polyhydric phenol have sulfonic acid groups attached to them to maintain water-solubility of the coordination complexes.

to azo nitrogen where M may be NHgor an alkali metal.

Truly black, light and airfast pigments are very rare in nature. Heretofore, chemists and manufacturers have generally made one of two choices in the manufacture of ink; they'have either made a mixture of pigments, none of which is black separately, .or they have used carbon to In'the heterogeneous inks the tint usually changes withage and the ink will not remain black indefinitely. This results from the fact that one of the pigments usually fades faster under light or oxidation; One of the present day inks made from a mixture of pigments consists of separable .blue and orange dyestuifs; therefore, it will turn blue .or orange with age.

An ink utilizinga very fine and dilute suspension of carbon has been made by'others. This type of .ink'will not ;soon clog fountain pens, but lacks the blackness debusiness paper and tracing materials.

A still furtherobject of this invention is to provide ink compositions having a minimum tendency to clog fountain pens and the like. It is also an object to provide such ink compositions wherein the black dyestuif has a strong stabilizing influence on the block colloidal materials suspended therein.

Another important object of this invention is to provide -an :ink for book publishing and the like wherein :thepigment can be removed from the fibers by reagents which are non-destructive to the fibers, thereby allowing the pulp to be returned to a higher grade of service than is now possible where carbon base printers inks aroused. Generally speaking, compounds of the type represented by the above structural formulas are-prepared .by first forming the aryl sulfom'c .acid diazonium salt (inner salt) and thereafter coupling the lattergene rally at a' rela- I tively high pH, for example, about l0with a suitable nio'ls per' mol-of phenolic compound. Thereafter a soluble trivalent iron family metal compound such as,

for example, a suitable iron or cobalt compound is next added to an aqueous solution of the aforesaid azo derivative to produce the respective metal complex thereof. To

the resulting metal complex is then added a sufficient quantity of a suitable base such as, for example, pyridine to bring the pH of the mixture to a value ranging from OH or H and Z is eitherH' or COOM wherein M in the case of both Y and Z represents H or an alkali metal. Examples of suitable phenols included within the scope of the above formula are catechol, pyrogallol, gallic acid and salicylic acid.

Aryl amino sulfonic acids that may be used in preparing the aryl sulfonic acid diazonium salts from which the new compositions of my invention are derived are represented by the formula NH -Aryl-SO H in which Aryl may be phenylor naphthyL. Examples of such compounds are ortho, meta, or para amino benzene sulfonic acid and 1- aminonaphthyl-4-sulfonic acid, as well as the various other positional isomers thereof such as, for example, l-aminonaphthyl-3-sulfonic acid .and the like.

Suitable iron-family metal compounds which may be prepared ferric hydroxide and the like.

about 4.5 to about 9.0. Thisstep I have generally found to bedesirable to produce a pigment of maximum blackness'. After adjusting the pH of the mixture in the manner indicated above,a water-soluble alcohol such as-for example-methanol, tertiary butyl alcohol, isopropyl-a1- coholand the like is added in a quantity sufiicient to effect precipitation of the pigment from the solution, In this regard, it should be pointed out that while a pigment can be secured fi-om the reaction mixture Without'precipitation therefrom with alcohol, such material is frequently found'not to be uniform in color. Hence, in order to insure the procurement of a pigment which is uniform' both with respect to color and to quality, I ordinarily prefer to precipitate the aforesaid metal complex from solution in the manner indicated above.

In carrying out this precipitation step, using methanol as the precipitating agent, the metal complex is generally soluble in alcohol concentrations up'to about percent.

' With about percent methanol, two phases are observed water-soluble nonelectrolyte; examples of such substances 'ing specific examples.

My invention may be further illustrated by the follow Example I the (6) Pour the product of (4) slowly, with stirring, into V the product of (5). 7

(7) Remove the ice, add an equal volume of water,

.settle, decant the clear water and save the sediment (8) Dissolve 3 /2 ounces catechol (1 00 grams) inl8 fluid ounces of water, add the solution to 7 pounds of crushed ice and mix the resulting product in 12 fluid ounces of 29% aqueous ammonium. hydroxide;

(9) Pour the product (sediment) of (7) slowly, with stirring, into the product of (8 a (10) Remove the ice and reduce the mixture to about cubic'inches by evaporation at about 82 C.

(11) The product of (10) may then be'filtered'to remove sediment, if desired.

(12) 20 cubiceentimeters of engravers solution of ferric chloride is then added to 200 cubic centimeters of the product of (10). I

(13) Pyridine may then. be added dropwise to the product of (12) to produce a pH offrom about 4.5

are ethyl lactate (esters), the Cellosolves (ethers),"2,5-

hexanedione, acetone (ketones) and the like. Accordingly, it is to be understood that the expression watersoluble nonelec trolyte as used in'the present description and ;claims is to be construed asanyjof a broad classof organic compounds, all of which are capable of effecting precipitation of the metal complex herein described. 7

The black tarry product obtained as' a result of the precipitation step may be dried at a temperature of about 65 C. to give a coal-like'substance which is readily soluble in water, producing anintensely'black solution.

. Other alkalies such as, for example, sodium carbonate In preparing such products, phenolic compounds of" the ,following type'may be employed 5 percent alcohol, yielding a -black,'tarry precipitate. latter is recovered and dried at "about 6 5 C. to yield 7 a black, friable pigment.

to about 9.0, developing the maximum blackness. Alternatively, ammonia may be employed in place of pyridine for the purpose of adjusting the pH 'of the mixture.

are likewise suitable.

To the resulting'mixture is' then added sufficient iso propyl alcohol to produce a mixture containing about 65 The A' 50 percent solution of the black dyestufi in watermay be used forhectographing, producing very fine, black copies.-'

a The blackmixture produced just prior to the precipitation step described abovemay be employed-to produce compositions suitablefor recorder service bythe addition of an appropriate high-boiling solvent. Thus, forexstylographic recorder service and for fingerprinting.

Ink prepared from the precipitated dyestuft may be removed from white cloth or removed from other fabrics with a dilute, e. g., 0.5 percent, hydrochloric acid soluwithout other mild alkali, is subsequently added until a tron. Removal from paper can readily be effected by use trace of odor is observed. The resulting liquid may be of the customary ink eradicaiors. Such ink is also 'susfiltered to yield black ink free of sediment. ceptrble of being contact prmtedbecause of its pronounced In Examples II, IV and V the black dyestuff can be absorption of blue and violet light (the eifect of its azo recovered in separated form by salting out With salllnkages) Wi'llCh is superimposed on the black characterammoniac or sodium chloride in a concentrated solution lstlos dev loped by the m tal H employed- If 1 1 of the dyestufi. In most cases, the dyestufi solutions can desired to lncreasethe viscosity of the ink, align derivab t at d b o ti i i t 66 C Wh than eqlllyalent y be addedthis is not feasible, drying in vacuo or in a stream of nitro- 10 en can be used. The dyestutfs which are prepared to xample I] be reacted with iron may be precipitated, if desired, by Black ink may also be produced by combining proporadding hydrogen Chloride t0 Saturation, 601d, t0 their tions of the reactants shown in the equation below under concenlmied SolutiOIlS- This Procfidllfe drives the y the conditions set forth in Example I. The reaction ininto undissociated (uh-ionized) form, which precipitates. volved and the product produced are postulated to be In the Preparation of y of these eXamples there y as follows: be added, as required, substances adapted to alter or im- OH OH SO3N'H4 Coordinate linkages to az o n itr ogen 0H l I OH i l I SOaNH; 3

Example III prove the wetting characteristics of the resulting fluid.

Some alcohols which are water-soluble, pyridine, quinoline, lauryl sulionate, are examples of materials which lower the surface tension and increase the wetting tendencies. A proprietary substance which has been tried, and which imparts these characteristics is Victawet #14" 4 which is believed to be butyl phosphonic acid. Example 1V From the foregoing description and examples, it will As a further example, the ink may be manufactured be Seal} :[hat Various FY1 of black Pigments af1d ink by mixing at 0 C. approximately 1.75 mols of par compositions hav ng lughly desirable characteristics can diazo benzene sulfonic acid with a solution containing 1 be m t d 111 zfccofdance with the P y mo} of Sodium ganate and an excess f sodium bicarbom 40 ventlon. Likewise, it Will be apparent to those skilled in am photoengravers ferric chloride solution, e a 35 he art that numerous modifications of the compositions to weight percent aqueous solution of ferric chloride, described harem m made which employ tha essentifll is then added Stepwise until there is no further increase features of my invention. In general, it may be said in color intensity. Subsequently, pyridine is added to the P scope 0f Iny lnvemlfm Qllcompasses as new P mixture until a pronounced odor thereof is detected. POSIUOIIS'of matter the del'lvatlyes formed y coupling The product thus f d when filt d contains a a phenolic compound of the type defined herein with an form, watepsoluble b1ackdye aryl aminosulfonic acid of the class referred to above,

followed by complexing the resulting product with a suit- 1 Example V able metal of the iron family.

Mix equimolar quantities of catechol and meta diazo This is a continuation-in-part of my copending applibenzene sulfonic acid. Thereafter add, stepwise, an equication U. S. Serial No. 279,959 filed April 1, 1952, now

The conditions described in Example I are employed except that cobaltous chloride is employed as the complexing agent. The ink obtained under such conditions is dark brown, giving sharp, well-defined lines, the color of which is stable for extended periods of time.

molar amount of sodium hydroxide in a 10 percent aqueabandoned. ous solution at 0 C. A precipitate having the follow- I claim: ing probable structural formula is produced: 1. In a process for the preparation of a pigment suit- 6O able for the use in the preparation of ink, the improvement which comprises coupling a diazotized phenyl sulfonic acid salt with a phenolic compound selected from the group consisting of catechol, pyrogallol, gallic acid,

salicylic acid and an alkali metal derivative of said acids, complexing the resulting product with a water-soluble r= so N trivalent metal compound of the iron family, thereafter adjusting the pH of the resulting mixture to a value rang- An equal number of gram mols of meta diazo benzene ing from about 4.5 to about 9.0, and forming a precipitate sulfonic acid is added to an aqueous solution prepared in said mixture by adding thereto a watersoluble organic from the above precipitate. The mixture is then counonelectrolite.

pled at 0 C. by slowly adding an equimolar amount of 2. The process of claim 1 in which the pH of the sodium hydroxide in the form of a 10 percent aqueous mixture is adjusted by means of pyridine.

solution. To the resulting mixture is then added photo- 3. The process of claim 1 in which the pH of the engravers ferric chloride solution until no further inmixture is adjusted by means of ammonia.

crease in color intensity is observed. Pyridine, with or 4. The process of claim 1 in which the complex is pre- I 2,836,688 V r 7 V V cipitated from the reaction mixture with a WEtCIrSOlUblfi employed in the metallizing step is a water soluble. trivaalcohol. e lent ironcompound. 1;

5. The process of claim 1 in which methanol is the 12. The reaction product of para diazo benzene sulorganic nonelectrolite. fonic acid and catechol complexed with trivalentiron, 6. The process of claim 1 in which isopropyl alcohol 5 said product having the probable structural formula: I

, V I S02 OH OH soau 1 I I soar Coordinatelinkages to azo nitrogen 'isthe organic nonelectroliteemployed. 1 a V wherein M is a member selected from the group consisting 7. A reaction product having the probable structural of NH; and an alkali metal, said product having beenformula: V 7 prepared by coupling said sulfonic acid with catechol and then complexingthe resulting product with a water-solu- V 2O ble trivalent 1ron compound, ad usting the'pH of the Z Z I about 4.5 to about 9, and recovering said reaction product.

Ary1 N=N I t N: .AWLSOBM 13. A black aqueous solution containing as the princi- 1 l Y pal coloring component the reaction product of claim 12. o fi fi linkages 14. The reaction product of para diazo benzene sul to nitrogen V W i fonic acid and sodium -gallatecom'plexed with trivalent wherein Aryl is a phenyl group, X is a member of the iron, said product havingihe probable structural forgroup consisting of H and 0H,.M is a member selected a mula:

S 0 M '1 S 0 M Coordinate linkages to azo nitrogen from the group consisting of NH; and analkali metal, 7 wherein M i's'a member selected from the group consist- M is a metal of the iron family, Y is a member selected ing of NH; and an alkali metal, said product having been.

from the group consisting. of OH and .COOM", and Z prepared by coupling said-sulfonic acid with sodium galreaction mixture to a'value within the range .of from i is a member of the group consisting of H and -COOM, late and then complexing the resulting product with a wherein M" represents a member of the group consisting I of H and an alkali metaLsaid product having been preof the reaction mixture to a value within the range of pared by coupling a diazotized phenyl sulfonic acid salt from aboutftj to about 9, and recovering said reaction with'a phenolic compQund selected from the group conproduct. i i 'sistingofcatechol, pyrogallol, gallic acid, salicylic acid J Y 1 j and an alkali metal derivative'ofsaid acids, complexing P References s in the-file Of h s pat tle taesulting grodluct t\Eith.af'twatelilsolt ilble ttgivalleiit rfnitlal 90 i UNITED A pA o e1ronamy, ereaera uSng ep'o e p a a resulting mixture to a value of from about 4.5 to about 9, g i f". ","i y 1929 precipitatingvsaid reaction product from said mixtureby 7008620 i a July 2 3 adding thereto a water-soluble,organicnonelectrolite and 5 k a July 35 recovering said reaction product. 3 3 7 L a f- "5"" 254936 8,. A black aqueous solution containing, as the princi- V 1 g? -"f i pal coloring component, the reactronproductof claim 7. 7 Q FOREIGN PATENTS, j. V M

9; The composition of claim 7 in which the metal eme 7 V I V i ployed' in the metallizing reaction is a trivalent iron com- 3:263 Great E 5 l89l pound. V, a 60 f 10. The compositionof claim 7 in which thecomplex- OTHER REFERENCES ingmetal is derived from ferric chloride. Drew et al.: Jour, Chem. Soc. (London) (1939), I,

11.,The composition of claim 8 in which the metal pages 823-835 (829 and 30).

'water soluble trivalent iron compound, adjusting the pH 7 a 

7. A REACTION PRODUCT HAVING THE PROBABLE STRUCTURAL FORMULA: 